Chest tube drainage system with analyzer

ABSTRACT

A system includes a chest tube drainage system comprising a first chamber in fluid communication with a port connectable to a chest tube, a second chamber in fluid communication with a port connectable to a suction device, and a fluid seal connected to and disposed between the first chamber and the second chamber. The system also includes one or more gas sensors attached to the chest tube drainage system, the one or more gas sensors configured to detect at least one of gaseous carbon dioxide and gaseous oxygen, a controller connected to the one or more gas sensors, and at least one indicator coupled to the controller. The controller is configured to determine if a threshold level of carbon dioxide is exceeded, and to activate the at least one indicator if the threshold level of carbon dioxide is not exceeded.

BACKGROUND

This patent is directed to an apparatus and method for determining whena chest tube should be removed, and in particular to an apparatus andmethod for determining when a chest tube should be removed combinablewith a chest tube drainage system.

Each year, over 380,000 lung resections and other events require a chesttube that drains air, and potentially fluids, leaking from the cutsurface of the lung into the pleural space. All patients following chestsurgery will have at least one chest tube, with some patients havingmore than one chest tube. The chest tube is attached to a drainagesystem in which the fluids exiting the chest tube are collected in acollection chamber. The drainage system is in turn attached to suction,to draw fluids and gases out of the pleural space into the drainagesystem.

At some point, the chest tube should be removed. The chest tube exitsbetween the rib spaces and may impinge the intercostal nerves. Thiscauses discomfort and requires intravenous pain medications. However, ifthe chest tube is removed too early, the removal of the chest tube canlead to lung collapse and cause major complications.

Air leaks are the largest determinant for leaving chest tubes inpatients following cardiothoracic lung procedures. Typically, thedecision to remove the chest tube is based on a crude visual inspection(VI) of the drainage system to determine if there is a leak into theplural space. If the visual inspection suggests that a leak exists, thenthe chest tube is left in place.

While a visual inspection may very well lead to the detection of a leakoriginating from the cut surface of the lung, the “detected” leak mayalso be the result of residual intrapleural air, a leak into the pleuralspace from the outside (e.g., through the chest tube incision around thechest tube), or reverse airflow in the chest tube. It is typicallyunclear from a simple visual inspection what the source of the “leak”might be. Further, the visual inspection technique may be influenced bypatient effort, tube position and presence of fluid or clots in thechest tube, for example.

As mentioned above, if the chest tube is removed based on a visualinspection that is incorrect (e.g., the inspection suggests that thereis no leak, or a detected leak is attributed to a cause other than thecut surface of the lung), the removal of the chest tube could lead tolung collapse, requiring replacement of the chest tube. Replacement ofthe chest tube could lead to complications. In any event, lung collapseand chest tube replacement will increase the length of the hospitalstay.

Considering the potential downside of a premature determination of theabsence of a leak, healthcare professionals may elect to leave the chesttube in even though there is no actual leak (e.g., the detected leak isattributable to the presence of residual intrapleural air). Of course,this also will increase the length of hospital stay, and leaving thechest tube in when not indicated could also lead to complications.

The costs of a prolonged hospital stay are considerable. Each additionalday that a patient spends hospitalized on the thoracic surgery floor isapproximately 6500 dollars, although that amount can vary. Moreover,prolonged hospitalization can lead to complications from deep veinthrombosis, pneumonia, hospital acquired infections, etc.

As set forth in more detail below, the present disclosure sets forth amethod and an analyzer for use with a chest tube drainage system, aswell as the entire system so defined, embodying advantageousalternatives to the existing visual inspection methods.

SUMMARY

According to one aspect of the present disclosure, a system includes achest tube drainage system comprising a first chamber in fluidcommunication with a port connectable to a chest tube, a second chamberin fluid communication with a port connectable to a suction device, anda fluid seal connected to and disposed between the first chamber and thesecond chamber. The system also includes one or more gas sensorsdisposed at the port connectable to the suction device or between theport and the fluid seal, the one or more gas sensors configured todetect at least one of gaseous carbon dioxide and gaseous oxygen.According to further aspects, the gas sensors may detect gaseous carbondioxide and oxygen, and the system may include at least one pressuresensor as well.

According to another aspect of the present disclosure, a system includesa chest tube drainage system comprising a first chamber in fluidcommunication with a port connectable to a chest tube, a second chamberin fluid communication with a port connectable to a suction device, anda fluid seal connected to and disposed between the first chamber and thesecond chamber. The system also includes one or more gas sensorsattached to the chest tube drainage system, the one or more gas sensorsconfigured to detect at least one of gaseous carbon dioxide and gaseousoxygen, a controller connected to the one or more gas sensors, and atleast one indicator coupled to the controller. The controller isconfigured to determine if a threshold level of carbon dioxide isexceeded, and to activate the at least one indicator if the thresholdlevel of carbon dioxide is not exceeded. According to further aspects,the gas sensors may detect gaseous carbon dioxide and oxygen, and thesystem may include at least one pressure sensor as well.

According to a further aspect of the present disclosure, a method ofdetermining if a chest tube is to be removed includes the steps ofdetermining if a threshold level of carbon dioxide is exceeded in achest tube drainage system connected to a chest tube downstream of aliquid seal, and removing the chest tube if the threshold level ofcarbon dioxide is not exceeded. According to further aspects, the methodmay include determinations based on threshold levels of oxygen andpressure as well.

BRIEF DESCRIPTION OF THE DRAWINGS

It is believed that the disclosure will be more fully understood fromthe following description taken in conjunction with the accompanyingdrawings. Some of the figures may have been simplified by the omissionof selected elements for the purpose of more clearly showing otherelements. Such omissions of elements in some figures are not necessarilyindicative of the presence or absence of particular elements in any ofthe exemplary embodiments, except as may be explicitly delineated in thecorresponding written description. None of the drawings is necessarilyto scale.

FIG. 1 is a schematic view of a system including an analyzer accordingto an embodiment of the present disclosure;

FIG. 2 is a schematic view of a system such as is illustrated in FIG. 1,with locations for the gas and pressure sensors marked;

FIG. 3 is a schematic view of a three-chamber drainage system that maybe used in the system of FIG. 1;

FIG. 4 is a cross-sectional view of a single-housing drainage systemthat may be used in the system of FIG. 1;

FIG. 5 is a flowchart of a method of operating the analyzer illustratedin FIG. 1;

FIGS. 6A and 6B is a flowchart of a detailed method of operating theanalyzer illustrated in FIG. 1; and

FIG. 7 is a schematic view of an alternative embodiment of an analyzer.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

FIG. 1 is an illustration of the system 100 including a chest tubedrainage system 102 and an analyzer 104 for use with a patient P. Thechest tube drainage system 102 includes ports 110, 112, chambers 114,116, and a fluid seal 118. The analyzer 104 includes one or more gassensors 120, a pressure sensor 122, a controller 124, and an indicator126. The system 100 may also include a chest tube 130, a suction device140, and a supplemental oxygen source 150.

The analyzer 104 utilizes the gas sensors 120, and optionally thepressure sensor 122, to determine whether the chest tube 130 may beremoved. In particular, the determination whether the chest tube 130 maybe removed is performed by the controller 124. If the determination ismade that the chest tube 130 may be removed, the controller activatesthe indicator 126 to signal the doctor or other healthcare professionalusing the analyzer 104 that the tube 130 may be removed. Non-activationof the indicator 126 or activation of a different indicator 126 maysignal the doctor or other healthcare professional that the chest tube130 may not be removed. In either event, activation of the indicator 126may provide a positive signal to the doctor or healthcare professional(e.g., a light is turned on) or a negative signal (e.g., a light that isinitially on is turned off).

Returning to FIG. 1, it will be recognized that the chest tube drainagesystem 102 has a chest tube port 110 that is connectable to the chesttube 130. As illustrated, the chest tube port 110 is connected to thechest tube 130 with a clamp 160 disposed between the port 110 and thechest tube 130, and the pressure sensor 122 disposed between the clamp160 and the chest tube 130. The first chamber 114 is in fluidcommunication with the chest tube port 110. Used in this sense, fluidcommunication may include a connection that permits both gaseous andliquid forms of fluids to pass therethrough.

The first chamber 114, which may be referred to as the collectionchamber, is configured to receive and separate a fluid component from agaseous component received by the drainage system 102 from the chesttube 130. The fluid seal 118 provides a one-way barrier through whichthe gaseous component may pass. The fluid seal 118, which may also bereferred to as a water seal, is connected to and disposed between thecollection chamber 114 and the second chamber 116.

The second chamber 116, which may be referred to as the suction chamber,is in fluid communication with the port 112. The port 112 is, in turn,connectable to the section generator 140. Disposed within the suctionchamber 116 are the one or more gas sensors 120, which will be referredto as the gas sensor 120 for simplicity although separate sensors may beused for detection and analysis of different gases. The gas sensor 120may be disposed anywhere within the suction chamber 116, but preferablymay be disposed at or near the port 112 to the suction device 140.

The controller 124 is connected to the gas sensor 120, the pressuresensor 122, the indicator 126, and the clamp 160. According to certainembodiments of the present disclosure, the controller 124 may also beconnected to the supplemental oxygen source 150. The controller 124 maybe configured to determine if a threshold level of carbon dioxide isexceeded in the suction chamber 116, and to activate the least oneindicator 126 if the threshold level of carbon dioxide is not exceeded.As explained previously, activation of the least one indicator 126 wouldbe used to signal the doctor or other healthcare professional that thechest tube 130 may be removed.

The controller 124 may also be configured to determine if a thresholdlevel of oxygen is exceeded in those situations where the thresholdlevel of carbon dioxide is exceeded. The oxygen measured by the gassensor 120 may be a consequence of the administration of supplementaloxygen from the supplemental oxygen source 150. In this regard, it willalso be recognized that while the oxygen source 150 is referred to asthe supplemental oxygen source, the oxygen source 150 may also be aprimary oxygen source as well. If the controller 124 determines that athreshold level of oxygen is not exceeded, then the controller 124activates the least one indicator 126 to signal that the chest tube 130may be removed.

The controller 124 may be further configured to determine if a thresholdpressure is exceeded at the pressure sensor 122 if the threshold levelof oxygen exceeded. In particular, the controller 124 may be configuredto activate the clamp 160, thereby isolating the pressure sensor 122from the remainder of the drainage system 102. The controller 124 maythen use the pressure sensor 122 to determine if the threshold pressureis exceeded. If the threshold pressure is not exceeded, the controller124 may activate the least one indicator 126 to signal that the chesttube 130 may be removed.

Having thus described the entire system 100, as well as its generaloperation, the specifics of the system 100 and the operation of thesystem 100 may now be discussed in detail.

As illustrated in FIG. 1, the gas sensor 120 is disposed in the suctionchamber 116 at or near the suction port 112. As indicated in FIG. 2, thegas sensor 120 may be disposed in a variety of other locations. Forexample, the gas sensor 120 may be disposed at the chest tube port 110,in the collection chamber 114, at the suction port 112, or at any of thelocations connecting the chest tube port 110, the collection chamber114, the suction chamber 116, the water seal 118, and the suction port112. Specifically, an asterisk (*) has been placed in FIG. 2 where thegas sensors 120 may be placed.

The gas sensor 120 may be disposed in-line or in parallel to the flow ofgases through the drainage system 102. An in-line system would permitthe gases to flow past the sensor 120 while the analyzer 104 uses thesensor 120 to analyze the composition of the gases. A parallel circuitarrangement would draw gases to the sensor 120 as the gases flow throughthe drainage system. A parallel circuit arrangement may be morecomplicated in that the suction used to draw the gases to the sensor 120may affect the operation of the drainage system.

It also will be appreciated that placement of the sensor 120 prior tothe water seal 118 may have some undesirable consequences. Inparticular, pleural fluids drawn into the drainage system 102 may comein contact with a gas sensor 120 disposed prior to the water seal 118.This is particularly true where a parallel circuit arrangement is usedand the gases must be drawn (with suction) to the sensor 120. The sensor120 may provide an inaccurate assessment of the gases present at thesensor 120 if the fluid contacts the sensor 120. Therefore, a gas sensor120 disposed prior to the water seal 118 would need to be shielded fromcontact with fluids passing into the drainage system 102.

As illustrated in FIG. 3, the chest tube drainage system 102 may includeseparate structures that define each of the collection chamber 114, thesuction chamber 116, and the water seal 118. The chest tube drainagesystem 102 illustrated in FIG. 3 may be referred to as a three-bottlesystem. A first container 200 with cannulas 202, 204 defines thecollection chamber 114 and the chest tube port 110 (cannula 202). Asecond container 206 with cannulas 208, 210 defines the water seal 118.In particular, it will be recognized that the cannula 208 dependsfurther into the container 206 than the cannula 210, and below a waterline 212. A third container 214 with cannulas 216, 218, 220 defines thesuction chamber 116 and the suction port 112 (cannula 220). It will berecognized that the third container 214 also includes a fluid, and thatthe cannula 218 depends into the fluid. The depth of the end of thecannula 218 below the surface of the fluid controls the applied suction.

As illustrated in FIG. 4, the chest tube drainage system 102 may also bein the form of a single-housing structure 250, with walls disposedwithin the single housing 250 defining each of the collection chamber114, the suction chamber 116, and the water seal 118. Openings in thehousing 250 may also define the ports 110, 112.

Specifically, an opening 252 in the housing 250 defines the gas tubeport 110. A wall 254 may separate the structures defining the water seal118 from the structures defining the collection chamber 114. In fact,the collection chamber 114 (which is in fluid communication with theopening 252/port 110) may include one or more walls 256, 258 thatsubdivide the space that defines the collection chamber 114. A passage260 is defined by the wall 254 and a second wall 262. The passage 260ends below a fluid line 264. A second passage 266 is defined by the wall262 and a second wall 268, and starts below the fluid line 264. Thesecond passage 266 is in fluid communication with an opening 270 thatdefines the suction port 112. It will also be recognized that thehousing 250 may have a further opening 272 that connects with a pair ofpassages 274, 276 separated by a wall 278, and from the passage 266 bythe wall 268. The passages 274, 276 are also partially fluid filled, andfunction in a fashion similar to that of the cannula 218 in theembodiment of the drainage system 102 illustrated in FIG. 3.

The embodiments of the drainage system 102 illustrated in FIGS. 3 and 4have been marked, similar to FIG. 2, to show the possible locations forplacement of the gas sensors 120 in the drainage system 102.Specifically, an asterisk (*) has been placed in the locations of theembodiments of FIGS. 3 and 4 where the gas sensors 120 may be placed. Inaddition, the gas sensor 120 may be disposed between the clamp 160 thatthe patient, P.

It will be recognized that still other embodiments of the drainagesystem 102 exist, such as may be manufactured by Atrium USA (Hudson,N.H.), Teleflex Medical (Research Triangle Park, N.C.), Covidien(Mansfield, Mass.), and Medela AG (Baar, Switzerland). These embodimentsmay include a mechanical one-way valve in place of the water sealreferred to above, which also may be referred to as a one-way valve, inconsideration of the fact that the water seal permits the flow of gasesin one direction and resists the flow of gases in the other direction.Furthermore, while the examples of the drainage system 102 illustratedherein are examples of a drainage system using wet suction control,other embodiments of the drainage system 102 may use dry suction controlinstead.

As to the analyzer 104, and in particular the controller 124, thecontroller 124 may be defined by individual circuits, or amicroprocessor or other programmable device with associated firmware orsoftware. In particular, the controller 124 may be defined by aprocessor and associated memory, which memory may be used to storeinstructions that cause the processor to receive information from and/orcontrol the sensors 120, 122 the indicator 126 and the supplementaloxygen source 150.

FIGS. 5 and 6A/6B are flow charts of methods of operating the analyzer104, the controller 124 being configured or programmed to carry outthese methods.

Beginning first with the method 300 illustrated in FIG. 5, the method300 begins at block 302 wherein the controller 124 uses the sensor 120analyze the level of carbon dioxide at the sensor 120. If the controller124 determines at block 304 that the level of carbon dioxide at thesensor 120 does not exceed a threshold level, the controller 124activates the indicator 126 at block 306 to signal to the doctor orother healthcare professional that the chest tube 130 may be removed. Ifthe controller 124 determines at block 304 that the level of carbondioxide of the sensor 120 exceeds the threshold level, then the methodcontinues to block 308.

At block 308, the controller 124 activates the supplemental oxygensource 150 to administer oxygen to the patient. The controller 124 thenuses the sensor 120 to analyze the level of oxygen at the sensor 120 atblock 310. If the controller 124 determines at block 312 that the levelof oxygen at the sensor 120 does not exceed a threshold level, thecontroller 124 activates the indicator 126 at the block 314. If thecontroller 124 determines at block 312 that the level of oxygen at thesensor 120 exceeds a threshold level, then the method may continue atblock 316.

At block 316, the controller 124 uses the clamp 160 and the pressuresensor 122 to determine the pressure at the pressure sensor 122. If thecontroller 124 determines at block 318 that the pressure that the sensor122 does not exceed a threshold level, the controller 124 activates theindicator 126 at the block 320. If the controller 124 determines atblock 318 that the pressure at the sensor 122 exceeds a threshold level,then the method ends at block 322. It will be recognized that the method300 may be repeated (and will be repeated) during the course oftreatment of an individual patient, but even an individual instance ofthe method 300 is included within the scope of the present disclosure.

A method 330 similar to the method 300 is illustrated in FIGS. 6A and6B. The method 330 also utilizes determinations of levels of gaseouscarbon dioxide and oxygen, as well as pressure, to determine when toactivate the indicator 126, thereby signaling to the doctor or otherhealthcare professional that the chest tube 130 may be removed. Themethod 330, however, provides additional details and levels ofsophistication relative to the method 300 described with reference toFIG. 5.

The method 330 begins at block 332 wherein the controller 124 uses thesensor 120 to analyze the level of carbon dioxide at the sensor 120. Ifthe level of carbon dioxide at the sensor 120 does not exceed a firstthreshold level (TH1) at block 334, then the controller 124 activatesthe indicator 126 at block 336. It is believed at the present time thatthe first threshold level may be 1% according to certain embodiments. Itwill be recognized that the threshold level alternatively may beexpressed in units of partial pressure of gases (e.g., mmHg ormillimeters of mercury); other alternatives are also possible. If thelevel of carbon dioxide at the sensor 122 exceeds the first thresholdlevel, then the method 330 continues to block 338.

At block 338, the controller 124 makes a further determination whetherthe level of carbon dioxide at the sensor 120 is between the firstthreshold level and a second threshold level (TH2). It is believed atthe present time that the second threshold level may be 3.5% accordingto certain embodiments. It will be recognized that the threshold levelalternatively may be expressed in units of partial pressure of gases(e.g., mmHg or millimeters of mercury); other alternatives are alsopossible. If the level of carbon dioxide at the sensor 120 is notbetween the first and second threshold levels, then the method 300continues as illustrated in FIG. 6B. If the level of carbon dioxide atthe sensor 120 is between the first and second threshold levels, thenthe method 300 continues at block 340.

At block 340, the controller 124 controls the supplemental oxygen source150 to administer supplemental oxygen to the patient. The controller 124then uses the sensor 120 to analyze the level of gaseous oxygen at thesensor 120 at block 342. The method 330 then continues to block 344,wherein the controller 124 determines if there has been an increase inthe level of gaseous oxygen at the sensor 120 (e.g., at least 1%increase). If the controller 124 determines there has been no increasein the level of gaseous oxygen at the sensor 120, the controller 124activates the indicator 126 at block 346. If the controller 124determines that there has been an increase in the level of gaseousoxygen at the sensor 120, the controller continues to block 348.

At block 348, the controller 124 determines if the increase in oxygenexceeds a first threshold (TH1). It is believed at the present time thatthe first threshold level may be 5% according to certain embodiments. Itwill be recognized that the threshold level alternatively may beexpressed in units of partial pressure of gases (e.g., mmHg ormillimeters of mercury); other alternatives are also possible. If thecontroller 124 determines that the increase in oxygen does not exceedthe first threshold level, the controller 124 activates the clamp 160 atblock 350, and analyzes the pressure at the sensor 122 at block 352. Ifthe controller 124 determines at block 354 that the pressure at thesensor 122 does not exceed a threshold level, then the controller 124activates the indicator 126 at block 356. If the controller 124determines that block 354 that the pressure at the sensor 122 exceeds athreshold level, then the clamp 160 is undamped at block 358 and thechest tube 130 is not removed at block 360.

If the controller 124 determines at block 348 that the oxygen increasedexceeds the first threshold level, the controller 124 proceeds to block362 and determines if the oxygen increase is between the first thresholdlevel and a second threshold level (TH2). It is believed at the presenttime that the second threshold level may be 10% according to certainembodiments. It will be recognized that the threshold levelalternatively may be expressed in units of partial pressure of gases(e.g., mmHg or millimeters of mercury); other alternatives are alsopossible. If the controller 124 determines that the increase in oxygenis between the first and second threshold levels at block 362, thecontroller 124 may optionally be configured or programmed to eitherproceed to block 350, or to block 364 where the method 330 ends and thechest tube 130 is not removed.

If the controller determines at block 362 that the oxygen increase isnot between the first and second threshold levels, then the controller124 proceeds to block 364, at which point the method 330 ends in thechest tube 130 is not removed.

Returning now to block 338, the method 330 continues to FIG. 6B andblock 366. At block 366, the controller 124 determines if the carbondioxide level is between the second threshold level and a thirdthreshold level (TH3). It is believed at the present time that the thirdthreshold level may be 6% according to certain embodiments. It will berecognized that the threshold level alternatively may be expressed inunits of partial pressure of gases (e.g., mmHg or millimeters ofmercury); other alternatives are also possible. If the controller 124determines a block 366 that the carbon dioxide level is between thesecond and third threshold levels, then the method 330 proceeds to block368 and supplemental oxygen is administered via the supplemental oxygensource 150.

The controller 124 then determines the oxygen level at the sensor 120 atblock 370. The method 330 then proceeds to block 372, wherein thecontroller 124 determines if there has been an increase in the level ofoxygen at the sensor 120. If the controller 124 determines there has notbeen an increase in the level of oxygen that the sensor 120, thecontroller may optionally be programmed either to proceed to block 374and activate the indicator 126, or to proceed to block 376 and activatethe clamp 160. If the controller 124 has been configured or programmedto proceed to block 376, then the controller 124 uses the sensor 122 todetermine the pressure at the sensor 122 at block 378. The controller124 then determines at block 380 if the pressure exceeds a thresholdlevel. If the pressure does not exceed the threshold level, then themethod 330 continues to block 382, and the controller 124 activates theindicator 126. If the pressure exceeds a threshold level at block 380,then the controller 124 releases the clamp 160 at block 384, and themethod 330 ends at block 386 without the chest tube 130 being removed.

If the controller 124 determines there has been an increase in the levelof oxygen at the sensor 120 at block 372, the method 330 may proceed toblock 388. At block 388, the controller 124 may control the supplementaloxygen source 150 and the suction 140 to reduce the level of carbondioxide and increase the level of oxygen. In particular, data suggeststhat if the gases in the intrapleural space include high levels ofcarbon dioxide, lung healing may be delayed and local innate immunitysuppressed. On the other hand, if supplemental oxygen is administered todisplace the carbon dioxide and/or suction is applied to draw carbondioxide out of the space, lung healing may be expedited, resulting in adecrease in the length of the hospital stay and post-surgicalinfections. Consequently, in a situation such as may be present at block388 (high levels of carbon dioxide present, and an oxygen increasesuggesting an actual leak in the cut surface of the lung), thecontroller 124 may intervene to reduce the carbon dioxide levels throughthe administration of supplemental oxygen and/or increase suction.

In any event, as was the case with method 300, it will be recognizedthat the method 330 may be repeated (and likely will be repeated) duringthe course of treatment of an individual patient, but even an individualinstance of the method 330 is included within the scope of the presentdisclosure.

In fact, the particular nature of the intervention may vary according tothe specific levels of carbon dioxide and oxygen detected in theintrapleural space. For example, if the carbon dioxide levels are veryhigh (in excess of 6%, for example), supplemental oxygen and suction maybe used to reduce the carbon dioxide levels to, for example, 3.5%.Alternatively, if the oxygen levels are particular low, but the carbondioxide levels are not particular high, supplemental oxygen may beadministered to increase the oxygen levels above 15%.

Embodiments according to the present disclosure may provide one or moreof the following advantages. The system and method according toembodiments of the present disclosure may reduce the clinicaluncertainty as to when to remove the chest tube. As a consequence, theduration of the inpatient hospital stay may be reduced, with a relatedreduction in the costs of the hospital stay. In addition, the system andmethod may be integrated with conventional chest drainage systems,facilitating adoption of the system and method. Further, the monitoringof pleural gases may provide an opportunity to investigate and modulatethe pleural gas mixture to promote lung healing. For example, accordingto certain embodiments, supplemental oxygen may be administered (andpotentially suction modulated) to vary the composition of the gasmixture within the chest cavity, potentially facilitating healing. Thisalso may have an effect in reducing hospital stay and associated costs.

The following examples provide a comparison of the gas analysistechniques according to the present disclosure with the conventionalvisual inspection techniques. In addition, the examples provide acomparison of the duration of hospital stay for patients with chesttubes who receive supplemental oxygen and, in some cases, modulatedsuction to the duration of hospital stay for patients that receivestandard chest tube care.

Example 1

Conventional visual inspection techniques and the gas analysistechniques according to embodiments of the present disclosure werecompared in fifty patients undergoing lobectomy.

The mean age of the study cohort was 53.1±11.0 years, while theMale:Female ratio was 29:21. Patients had postresection predicted FEV1and DLCO>40%. Thirty patients (60%) had a right-sided lobectomy, while20 patients (40%) had left-sided lobectomy, 29 patients (58%) had upperlobectomies, 19 patients (38%) had lower lobectomies, and 2 patients(4%) had middle lobectomies.

All patients had a single 24 or 28 F chest tube placed intraoperatively.The chest tubes were kept on suction at −20 cm after surgery, andswitched to water seal drainage on post-operative day 1.

When the staff surgeon deemed that the fluid output had reached theremoval threshold, the comparison between visual inspection and gasanalysis was performed. Stated slightly differently, Day 0 representsthe start of serial analysis when the fluid output decreased to belowremoval threshold for the surgeon. The mean duration for the fluidoutput to fall below the individual surgeon's threshold from the day ofsurgery was 1.8±0.7 days.

Visual Inspection

For analysis of air leak by visual inspection, the patient was asked tocough five times and then take five deep breaths. This sequence wasrepeated twice. The first sequence was directed towards eliminating anytrapped air in the pleural space or the tubing. Visual inspection wasconsidered positive if air bubbles were detected during the secondsequence.

Gas Analysis

Gas analysis was performed at the sampling port of the chest drainingsystem. The sampling tubing was first connected to the chest drainagesystem and CO₂ and O₂ recorded. Supplemental O₂ was then administerednasally. Patients were allowed to take deep breaths for one minute,after which the values of CO₂ and O₂ were recorded.

A pleural CO₂<1% and/or an increase in O₂<2% with the administration ofsupplemental O₂ of 5 liters/min was determined to indicated the absenceof a true leak. Additionally, a pleural CO₂>1% with an increase in O₂≥2%with the administration of supplemental O₂ of 5 liters/min wasdetermined to indicate a true leak. As to a pleural CO₂>1% with anincrease in O₂<2% with the administration of supplemental O₂ of 5liters/min, this was determined to suggest a recently resolved air leak(i.e., no true air leak).

End Points

Patients were followed for development of pneumothorax for three weeksafter surgery. The primary end points were development of pneumothoraxfollowing chest tube removal on a chest radiograph obtained within fourhours, readmissions for pneumothorax, and evidence of pneumothorax onthe chest radiograph obtained at the post-operative visit at 2-3 weeks.

Statistical Analysis

Statistical analysis was performed using Microsoft Excel 2011 (MicrosoftCorp, Redmond, Wash.) and GraphPad Prism, version 6 (GraphPad SoftwareInc, San Diego, Calif.). Two-tailed student and Fisher exact t-testswere used as appropriate. Statistical significance was defined atp<0.05.

Discussion of Results

Visual inspection revealed bubbles as to 31 patients, suggesting airleaks in those patients. By contrast, gas analysis indicated an air leakin only 19 patients. The comparison of the results suggested that thevisual inspection techniques provided 12 false indications of an airleak.

To confirm that visual inspection was providing a false indication of anair leak, the chest tubes were clamped for 8 of the 12 patients in thegroup for which gas analysis suggested there was no air leak. Asubsequent chest radiograph of those patients taken after four hours wasnormal, and the tubes were removed completely without development ofpneumothorax. This led to the conclusion that the visual inspectiondeterminations that an air leak was present were in fact false. As tothe remaining 4 patients, no clamp trial was performed, and instead thechest tubes were removed directly. None of the 12 patients developedpneumothorax during three weeks of post-operative follow-up.

In addition, the 19 patients for which both visual inspection and gasanalysis suggested air leaks were serially monitored to determine anydiscrepancy between the two techniques. The chest tubes were removedonly if visual inspection was negative for air leak. As seen in Table 1,a greater proportion of patients tested positive for air leak by visualinspection than by gas analysis every day. As demonstrated above, apositive visual inspection but negative gas analysis suggests a falsedetermination of an air leak by visual inspection. Therefore, it isbelieved that visual inspection over-estimates the prevalence of airleaks on each post-operative day.

TABLE 1 Day 0 Day 1 Day 2 Day 3 Day 4 Day 5 Visual Inspection 19 14 12 74 3 indicates air leak (100%) (74%) (63%) (37%) (16%) (11%) Gas Analysis19 10  5 4 2 2 indicates air leak (100%) (53%) (26%) (21%) (10%) (10%)

Visual inspection also revealed no bubbles as to 19 patients, suggestingno air leaks in those patients. By contrast, gas analysis suggested that2 of 19 patients actually did have an air leak. The comparison of theresults suggested that the visual inspection techniques provided 2 falseindications of no air leak.

To confirm that visual inspection was providing a false indication of noair leak, the chest tubes were removed from both the patients for whomgas analysis suggested there was an air leak. A radiograph taken withintwo hours indicated the development of a large pneumothorax in bothpatients. As a consequence, visual inspection might not be sensitive todetect small air leaks that do not cause bubbles, but can still lead topneumothorax.

On the other hand, there was concordance between visual inspection andgas analysis as to 36 of the 51 patients. In fact, in 17 patients therewas no air leak detected by both visual inspection and gas analysis. Oneof these patients, however, developed pneumothorax following tuberemoval.

In conclusion, of the 50 patients involved in the experiment, 22patients had air leaks (19 of which were determined using bothtechniques, 2 of which were determined using only the gas analysistechnique, and 1 of which was not determined by either technique).Stated slightly differently, the visual inspection technique failed toidentify air leaks in 3 patients and identified air leaks in 12 patientswhere no air leak existed. By contrast, the gas analysis techniqueaccurately demonstrated air leaks in 21 with only 1 false negative andno false positives. Accordingly, the gas analysis technique demonstratedbetter sensitivity (95.5% vs 86.4%), specificity (100% vs 57.1%),positive predictive value (100% vs 61.3%), and negative predictive value(96.6% vs 84.2%) in detection of air leaks.

Example 2

Conventional visual inspection techniques and the gas analysistechniques according to embodiments of the present disclosure werecompared in 240 patients who either had undergone a procedure or werereceiving treatment for a condition that required a chest tube.

The trial included 120 patients having had lung resections, 50 patientswith spontaneous pneumothorax, 30 patients having had cardiac surgery,15 patients having had a decortication, 10 patients with iatrogenicpneumothorax, 5 patients with ARDS/barotrauma pneumothorax, and 10patients with pleural effusion/pleurodiesis.

The standards for visual inspection, gas analysis, end points,statistical analysis are as above relative to Example 1.

Discussion of Results

Visual inspection revealed bubbles as to 130 patients, suggesting airleaks in those patients. By contrast, gas analysis indicated an air leakin only 101 patients. The comparison of the results suggested that thevisual inspection techniques provided 29 false indications of an airleak.

To confirm that visual inspection was providing a false indication of anair leak, the chest tubes were removed in all 29 patients. None of the29 patients developed pneumothorax. This led to the conclusion that thevisual inspection determinations that an air leak was present were infact false.

Visual inspection also revealed no bubbles as to 110 patients,suggesting no air leaks in those patients. By contrast, gas analysissuggested that 7 of 110 patients actually did have an air leak. Thecomparison of the results suggested that the visual inspectiontechniques provided 7 false indications of no air leak.

To confirm that visual inspection was providing a false indication of noair leak, the chest tubes were removed from 2 patients for whom gasanalysis suggested there was an air leak. As to both patients, it wasnecessary to replace the chest tube after it was removed. As aconsequence, visual inspection might not be sensitive to detect smallair leaks that do not cause bubbles, but can still lead to pneumothorax.

In conclusion, of the 240 patients involved in the experiment, 108patients had air leaks (101 of which were determined using bothtechniques, 7 of which were determined using only the gas analysistechnique) and 132 patients had no air leaks (103 of which weredetermined using both techniques, 29 of which were determined using onlythe gas analysis technique). Stated slightly differently, the visualinspection technique failed to identify air leaks in 7 patients andidentified air leaks in 29 patients where no air leak existed.

Example 3

The promotion of lung healing with the administration of supplemental O₂and, in some cases, modulated suction was studied in regard to 20patients with intrapleural (IP) CO₂ in excess of 5%. These 20 patientswere alternatively assigned (i) to undergo intervention directed towardsreducing the intrapleural CO₂ levels to less than 5% and increasingintrapleural O₂ levels to greater than 21% or (ii) managed according tostandard practice (i.e., water seal drainage and weaned off of O₂). Thedata for the group that received intervention is presented in Table 2,below, and the data for the group that was managed according to thestandard practice is presented in Table 3, below.

TABLE 2 Post- Post- Initial Initial Int. Int. Size of IP CO2 IP O2 ChestSuppl. CO2 O2 Duration Patient - Leak level level Drainage O2 levellevel of Leak Int. (chambers) (%) (%) (cm H2O) (1/min) (%) (%) (days) 12 6.2 16 −20 2 4.9 25 2 2 1 6.4 17 −20 4 4.8 25 2 3 1 7.1 18 −20 4 4.124 3 4 2 6.1 15 −30 2 4.5 26 2 5 4 8.1 11 −40 3 3 32 3 6 3 6.6 14 −20 42.9 25 3 7 2 6 15 −20 4 3.9 29 3 8 2 6.9 16 −20 2 4.4 33 2 9 2 6.8 17−20 3 4.5 28 2 10 3 5.9 15 −20 4 4.1 24 2 Mean ± STDev 2.2 ± 0.9 6.6 ±1.2 15.4 ± 1.9 4.1 ± 0.7 27.1 ± 3.3 2.4 ± 0.5

TABLE 3 Patient - Initial IP Standard Size of Leak CO₂ level Initial IPO₂ Duration of Practice (chambers) (%) level (%) Leak (days) 1 1 6.1 185 2 2 6.8 15 6 3 2 6.1 16 7 4 2 7.1 17 5 5 1 6.8 14 8 6 1 6.2 13 6 7 26.6 16 4 8 4 8.1 14 6 9 3 8.2 15 6 10  2 6.2 13 7 Mean ± STDev 2.0 ± 0.96.8 ± 0.9 15.1 ± 1.7 6 ± 1.2

There was no difference in the size of air leak between the two groups(intervention group 2.2±0.9 chambers vs. standard practice 2.0±0.9chambers). In addition, there was no difference between the two groupswith regard to initial intrapleural CO₂ levels (intervention 6.6±1.2%vs. standard practice 6.8±0.9%). Further, there was no differencebetween the two groups with regard to initial intrapleural O₂ levels(intervention 15.4%±1.9% vs. standard practice 15.1%±1.7%).

The interventions to reduce the CO₂ levels included extrapleural suctionup to −40 cm H₂O and supplemental oxygen up to 4 l/min. The goal was toadminister extrapleural suction and supplemental O₂ to achieve anintrapleural CO₂ level less than 5% and an intrapleural O₂ level greaterthan 21%. As seen in Table 2, the described intervention led to areduction in intrapleural CO₂ levels from 6.6%±1.2% to 4.1%±0.7% andincrease in O₂ from 15.4%±1.9% to 27.1%±3.3%. Comparing Table 2 to Table3, it will be recognized that the patients that underwent interventionshowed significantly decreased duration of air leaks compared to thosethat did not (intervention 2.4±0.5 days vs. standard practice 6.0±1.2days).

Although the preceding text sets forth a detailed description ofdifferent embodiments of the invention, it should be understood that thelegal scope of the invention is defined by the words of the claims setforth at the end of this patent. The detailed description is to beconstrued as exemplary only and does not describe every possibleembodiment of the invention since describing every possible embodimentwould be impractical, if not impossible. Numerous alternativeembodiments could be implemented, using either current technology ortechnology developed after the filing date of this patent, which wouldstill fall within the scope of the claims defining the invention.

As one example of an alternative embodiment, FIG. 7 includes a blockdiagram of an analyzer 104′. The analyzer 104′ includes a carbon dioxidedetector 400, an oxygen detector 402, a comparator 404, an oxygenmodulator 406, a suction modulator 408, and an indicator driver 410. Asdescribed above, each of the detectors 400, 402, the comparator 404,each of the modulators 406, 408, and the indicator driver 410 may bedefined by individual circuits, or a microprocessor or otherprogrammable device with associated firmware or software. In fact, allof the elements of the analyzer 104′ may be defined by a processor andassociated memory, which memory may be used to store instructions thatcause the processor to carry out the actions of the individual elements.

According to this embodiment, the carbon dioxide detector 400 and theoxygen detector 402 are coupled to sensors 120 that determine the levelof carbon dioxide, oxygen, or both. Each of the detectors 400, 402receive signals from the sensors 120 and provide an output to thecomparator 404, which element determines whether the level of carbondioxide and/or oxygen exceeds the thresholds set for those levels, asdiscussed above. Furthermore, the oxygen modulator 406 is coupleable toan oxygen source, and may modify the administration of the oxygen to thepatient (i) as part of the process of determining the level of oxygen inthe intrapleural space and/or (ii) as part of the process of modifyingor altering the level of oxygen in the intrapleural space to change thelevel of oxygen in the intrapleural space. In a similar fashion, thesuction modulator 408 may alter the level of suction applied via thedrainage system 102 to modify or alter the level of carbon dioxide inthe intrapleural space.

The modulators 406, 408 may be coupled to the comparator 404 to receivea signal or other output therefrom to control the rate at which themodulators 406, 408 control the associated oxygen supply or suction tomodify or alter the gaseous milieu in the intrapleural space. Theindicator driver 410 also may be coupled to the comparator 404, and mayreceive a signal or other output therefrom to control the indicator 126no that the surgeon or other healthcare professional may be able todetermine whether to remove the chest tube.

Other examples of alternative embodiments are discussed in the followingnumbered paragraphs. Moreover, while discussed in terms of a systemincluding both drainage system and analyzer, the present disclosure alsoencompasses the analyzer separate from the drainage system to which itmay be coupled.

1. A system comprising:

a chest tube drainage system comprising a first chamber in fluidcommunication with a port connectable to a chest tube, a second chamberin fluid communication with a port connectable to a suction device, anda fluid seal connected to and disposed between the first chamber and thesecond chamber;

one or more gas sensors attached to the chest tube drainage system, theone or more gas sensors configured to detect at least one of gaseouscarbon dioxide and gaseous oxygen;

a controller connected to the one or more gas sensors; and

at least one indicator coupled to the controller,

the controller configured to determine if a threshold level of carbondioxide is exceeded, and to activate the at least one indicator if thethreshold level of carbon dioxide is not exceeded.

2. The system according to paragraph 1, wherein the threshold level ofcarbon dioxide is 1%.

3. The system according to paragraph 1, wherein the controller isconfigured to determine if a threshold level of oxygen is exceeded ifthe threshold level of carbon dioxide is exceeded, and to activate theat least one indicator if the threshold level of oxygen is not exceeded.

4. The system according to paragraph 3, wherein the threshold level ofoxygen is 1%.

5. The system according to paragraph 3, wherein the threshold level ofoxygen is 2%.

6. The system according to paragraph 3, further comprising a clampdisposed between the port connectable to a chest tube and the chesttube, and a pressure sensor disposed between the clamp and the chesttube and connected to the controller, wherein the controller configuredto determine if a threshold pressure is exceeded at the pressure sensorif the threshold level of oxygen is exceeded, and to activate the atleast one indicator if the threshold pressure is not exceeded.

7. The system according to paragraph 6, wherein the threshold level ofoxygen is less than 5%.

8. The system according to paragraph 1, further comprising an oxygensource coupled to the controller, the controller configured to activatethe oxygen source if the threshold level of carbon dioxide is exceeded.

9. The system according to paragraph 8, wherein controller is configuredto determine if a threshold level of oxygen is exceeded after the oxygensource is activated, and to activate the at least one indicator if thethreshold level of oxygen is not exceeded.

10. The system according to paragraph 9, wherein the controller isconfigured to activate the oxygen source if the threshold level ofcarbon dioxide is exceeded and a second threshold level of carbondioxide is not exceeded, and to determine if a threshold level of oxygenis exceeded after the oxygen source is activated, and to activate the atleast one indicator if the threshold level of oxygen is not exceeded.

11. The system according to paragraph 10, wherein the threshold level ofoxygen is 1%.

12. The system according to paragraph 10, wherein the threshold level ofoxygen is 2%.

13. The system according to paragraph 10, further comprising a clampdisposed between the port connectable to a chest tube and the chesttube, and a pressure sensor disposed between the clamp and the chesttube and connected to the controller, wherein the controller configuredto determine if a threshold pressure is exceeded at the pressure sensorif the threshold level of oxygen is exceeded, and to activate the atleast one indicator if the threshold pressure is not exceeded.

14. The system according to paragraph 10, wherein the controller isconfigured to activate the oxygen source if the threshold level ofcarbon dioxide is exceeded and the second threshold level of carbondioxide is exceeded to increase the level of oxygen above anintervention level.

15. The system according to paragraph 14, wherein the controller isconfigured to modulate suction to the drainage system if the secondthreshold level of carbon dioxide is exceeded to decrease the level ofcarbon dioxide below an intervention level.

16. A system comprising:

a chest tube drainage system comprising a first chamber in fluidcommunication with a port connectable to a chest tube, a second chamberin fluid communication with a port connectable to a suction device, andone-way valve connected to and disposed between the first chamber andthe second chamber;

one or more gas sensors attached to the chest tube drainage system, theone or more gas sensors configured to detect at least one of gaseouscarbon dioxide and gaseous oxygen;

a controller connected to the one or more gas sensors; and

at least one indicator coupled to the controller,

the controller configured to determine if a threshold level of carbondioxide is exceeded, and to activate the at least one indicator if thethreshold level of carbon dioxide is not exceeded.

17. The system according to paragraph 16, wherein the threshold level ofcarbon dioxide is 1%.

18. The system according to paragraph 16, wherein the controller isconfigured to determine if a threshold level of oxygen is exceeded ifthe threshold level of carbon dioxide is exceeded, and to activate theat least one indicator if the threshold level of oxygen is not exceeded.

19. The system according to paragraph 18, wherein the threshold level ofoxygen is 1%.

20. The system according to paragraph 18, wherein the threshold level ofoxygen is 2%.

21. The system according to paragraph 18, further comprising a clampdisposed between the port connectable to a chest tube and the chesttube, and a pressure sensor disposed between the clamp and the chesttube and connected to the controller, wherein the controller configuredto determine if a threshold pressure is exceeded at the pressure sensorif the threshold level of oxygen is exceeded, and to activate the atleast one indicator if the threshold pressure is not exceeded.

22. The system according to paragraph 21, wherein the threshold level ofoxygen is less than 5%.

23. The system according to paragraph 16, further comprising an oxygensource coupled to the controller, the controller configured to activatethe oxygen source if the threshold level of carbon dioxide is exceeded.

24. The system according to paragraph 23, wherein controller isconfigured to determine if a threshold level of oxygen is exceeded afterthe oxygen source is activated, and to activate the at least oneindicator if the threshold level of oxygen is not exceeded.

25. The system according to paragraph 24, wherein the controller isconfigured to activate the oxygen source if the threshold level ofcarbon dioxide is exceeded and a second threshold level of carbondioxide is not exceeded, and to determine if a threshold level of oxygenis exceeded after the oxygen source is activated, and to activate the atleast one indicator if the threshold level of oxygen is not exceeded.

26. The system according to paragraph 25, wherein the threshold level ofoxygen is 1%.

27. The system according to paragraph 25, wherein the threshold level ofoxygen is 2%.

28. The system according to paragraph 25, further comprising a clampdisposed between the port connectable to a chest tube and the chesttube, and a pressure sensor disposed between the clamp and the chesttube and connected to the controller, wherein the controller configuredto determine if a threshold pressure is exceeded at the pressure sensorif the threshold level of oxygen is exceeded, and to activate the atleast one indicator if the threshold pressure is not exceeded.

29. The system according to paragraph 25, wherein the controller isconfigured to activate the oxygen source if the threshold level ofcarbon dioxide is exceeded and the second threshold level of carbondioxide is exceeded to increase the level of oxygen above anintervention level.

30. The system according to paragraph 29, wherein the controller isconfigured to modulate suction to the drainage system if the secondthreshold level of carbon dioxide is exceeded to decrease the level ofcarbon dioxide below an intervention level.

31. A system comprising:

a chest tube drainage system comprising a first chamber in fluidcommunication with a port connectable to a chest tube, a second chamberin fluid communication with a port connectable to a suction device, anda one-way valve connected to and disposed between the first chamber andthe second chamber;

one or more gas sensors attached to the chest tube drainage system, theone or more gas sensors configured to detect gaseous carbon dioxide;

a controller connected to the one or more gas sensors; and

at least one indicator coupled to the controller,

the controller configured to determine if a threshold level of carbondioxide is exceeded, and to activate the at least one indicator if thethreshold level of carbon dioxide is not exceeded to signal that thechest tube may be removed.

32. A system comprising:

a chest tube drainage system comprising a first chamber in fluidcommunication with a port connectable to a chest tube, a second chamberin fluid communication with a port connectable to a suction device, anda one-way valve connected to and disposed between the first chamber andthe second chamber;

one or more gas sensors attached to the chest tube drainage system, oneof the one or more gas sensors configured to detect gaseous carbondioxide and one of the one or more gas sensors configured to detectgaseous oxygen;

a controller connected to the one or more gas sensors; and

at least one indicator coupled to the controller,

the controller configured (a) to determine if a threshold level ofcarbon dioxide is exceeded, and to activate the at least one indicatorif the threshold level of carbon dioxide is not exceeded to signal thatthe chest tube may be removed, and (b) to determine if a threshold levelof oxygen is exceeded if the threshold level of carbon dioxide isexceeded, and to activate the at least one indicator if the thresholdlevel of oxygen is not exceeded to signal that the chest tube may beremoved.

33. A system comprising:

a chest tube drainage system comprising a first chamber in fluidcommunication with a port connectable to a chest tube, a second chamberin fluid communication with a port connectable to a suction device, anda one-way valve connected to and disposed between the first chamber andthe second chamber;

one or more gas sensors attached to the chest tube drainage system, theone or more gas sensors configured to detect gaseous carbon dioxide;

a clamp disposed between the port connectable to a chest tube and thechest tube, and a pressure sensor disposed between the clamp and thechest tube and connected to the controller,

a controller connected to the one or more gas sensors; and

at least one indicator coupled to the controller,

the controller configured (a) to determine if a threshold level ofcarbon dioxide is exceeded, and to activate the at least one indicatorif the threshold level of carbon dioxide is not exceeded to signal thatthe chest tube may be removed, (b) to determine if a threshold level ofoxygen is exceeded if the threshold level of carbon dioxide is exceeded,and to activate the at least one indicator if the threshold level ofoxygen is not exceeded to signal that the chest tube may be removed, and(c) to determine if a threshold pressure is exceeded at the pressuresensor if the threshold level of oxygen is exceeded, and to activate theat least one indicator if the threshold pressure is not exceeded tosignal that the chest tube may be removed.

34. A system comprising:

a chest tube drainage system comprising a first chamber in fluidcommunication with a port connectable to a chest tube, a second chamberin fluid communication with a port connectable to a suction device, anda one-way valve connected to and disposed between the first chamber andthe second chamber;

one or more gas sensors attached to the chest tube drainage system, theone or more gas sensors configured to detect gaseous carbon dioxide;

at least one indicator;

an oxygen source;

a controller connected to the one or more gas sensors, the at least oneindicator, and the oxygen source,

the controller configured (a) to determine if a threshold level ofcarbon dioxide is exceeded, and to activate the at least one indicatorif the threshold level of carbon dioxide is not exceeded to signal thatthe chest tube may be removed, and (b) to activate the oxygen source ifthe threshold level of carbon dioxide is exceeded.

35. The system according to paragraph 34, further comprising a clampdisposed between the port connectable to a chest tube and the chesttube, and a pressure sensor disposed between the clamp and the chesttube and connected to the controller, wherein the controller configuredto determine if a threshold pressure is exceeded at the pressure sensorif a threshold level of oxygen is exceeded, and to activate the at leastone indicator if the threshold pressure is not exceeded.

36. A method of determining if a chest tube is to be removed, the methodcomprising the steps of:

determining if a threshold level of carbon dioxide is exceeded in achest tube drainage system connected to a chest tube downstream of aliquid seal; and

removing the chest tube if the threshold level of carbon dioxide is notexceeded.

37. The method according to paragraph 36, further comprising:administering supplemental oxygen if the carbon dioxide level isexceeded.

38. The method according to paragraph 36, further comprising: applyingadditional suction through the chest tube if the carbon dioxide level isexceeded.

39. The method according to paragraph 36, further comprising:determining if a threshold level of oxygen is exceeded in the chest tubedrainage system; and removing the chest tube if the threshold leveloxygen is not exceeded.

40. The method according to paragraph 36, further comprising:administering supplemental oxygen if the threshold level of carbondioxide is not exceeded; determining if a threshold level of oxygen isexceeded in the chest tube drainage system after administeringsupplemental oxygen; and removing the chest tube if the threshold leveloxygen is not exceeded.

41. The method according to paragraph 40, further comprising: disposinga clamp between the chest tube and the chest tube drainage system;determining if a threshold pressure is exceeded downstream of the clamp;and removing the chest tube if the threshold pressure is not exceeded.

42. The method according to paragraph 39, further comprising:administering additional supplemental oxygen if the oxygen level isexceeded.

43. The method according to paragraph 39, further comprising: applyingadditional suction through the chest tube if the oxygen level isexceeded.

44. A system comprising:

a chest tube drainage system comprising a first chamber in fluidcommunication with a port connectable to a chest tube, a second chamberin fluid communication with a port connectable to a suction device, anda fluid seal connected to and disposed between the first chamber and thesecond chamber; and

one or more gas sensors disposed at the port connectable to the suctiondevice or between the port and the fluid seal, the one or more gassensors configured to detect at least one of gaseous carbon dioxide andgaseous oxygen.

45. The system according to paragraph 44, wherein the one or more gassensors are disposed at the port connectable to the suction device.

46. The system according to paragraph 44, further comprising a clampdisposed between the port connectable to a chest tube and the chesttube, and a pressure sensor disposed between the clamp and the chesttube.

47. The system according to paragraph 44, further comprising acontroller connected to the one or more gas sensors and at least oneindicator coupled to the controller, wherein the controller configuredto determine if a threshold level of carbon dioxide is exceeded, and toactivate the at least one indicator if the threshold level of carbondioxide is not exceeded.

48. The system according to paragraph 47, wherein the controllerconfigured to determine if a threshold level of oxygen is exceeded ifthe threshold level of carbon dioxide is exceeded, and to activate theat least one indicator if the threshold level of oxygen is not exceeded.

49. The system according to paragraph 48, further comprising a clampdisposed between the port connectable to a chest tube and the chesttube, and a pressure sensor disposed between the clamp and the chesttube and connected to the controller, wherein the controller configuredto determine if a threshold pressure is exceeded at the pressure sensorif the threshold level of oxygen is exceeded, and to activate the atleast one indicator if the threshold pressure is not exceeded.

It should also be understood that, unless a term is expressly defined inthis patent using the sentence “As used herein, the term ‘ . . . ’ ishereby defined to mean . . . ” or a similar sentence, there is no intentto limit the meaning of that term, either expressly or by implication,beyond its plain or ordinary meaning, and such term should not beinterpreted to be limited in scope based on any statement made in anysection of this patent (other than the language of the claims). To theextent that any term recited in the claims at the end of this patent isreferred to in this patent in a manner consistent with a single meaning,that is done for sake of clarity only so as to not confuse the reader,and it is not intended that such claim term be limited, by implicationor otherwise, to that single meaning. Finally, unless a claim element isdefined by reciting the word “means” and a function without the recitalof any structure, it is not intended that the scope of any claim elementbe interpreted based on the application of 35 U.S.C. § 112(f).

What is claimed is:
 1. A method of determining if it is proper for achest tube to be removed, the method comprising the steps of: detectinga gas at a point downstream of a liquid seal in a chest tube drainagesystem connected to the chest tube, the gas having leaked from a lunginto the pleural space, the gas selected from the group consisting ofgaseous carbon dioxide and gaseous oxygen; determining if an upperthreshold level of carbon dioxide is exceeded at the point downstream ofthe liquid seal; and removing the chest tube if the upper thresholdlevel of carbon dioxide is not exceeded.
 2. The method according toclaim 1, further comprising: administering supplemental oxygen if theupper threshold level of carbon dioxide is exceeded.
 3. The methodaccording to claim 1, further comprising: applying suction of higherintensity through the chest tube if the upper threshold level of carbondioxide is exceeded.
 4. The method according to claim 1, furthercomprising: determining if a threshold level of oxygen is exceeded inthe chest tube drainage system; and removing the chest tube if thethreshold level of oxygen is not exceeded.
 5. The method according toclaim 4, further comprising: administering additional supplementaloxygen if the threshold level of oxygen is exceeded.
 6. The methodaccording to claim 4, further comprising: applying suction of higherintensity through the chest tube if the threshold level of oxygen isexceeded.
 7. The method according to claim 1, further comprising:administering supplemental oxygen if the threshold level of carbondioxide is not exceeded; determining if a threshold level of oxygen isexceeded in the chest tube drainage system after administeringsupplemental oxygen; and removing the chest tube if the threshold levelof oxygen is not exceeded.
 8. The method according to claim 7, furthercomprising: disposing a clamp between the chest tube and the chest tubedrainage system; determining if a threshold pressure is exceeded betweenthe clamp and a patient's chest cavity; and removing the chest tube ifthe threshold pressure is not exceeded.